Network management and other issues


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Network management and other issues

  1. 1. ECE 6160: Advanced Computer Networks Network Management Instructor: Dr. Xubin (Ben) He Email: [email_address] Tel: 931-372-3462 Slides are adapted from the original slides developed by Kurose and Ross. All material copyright 1996-2007 J.F Kurose and K.W. Ross, All Rights Reserved
  2. 2. Network Management <ul><li>introduction to network management </li></ul><ul><ul><li>motivation </li></ul></ul><ul><ul><li>major components </li></ul></ul><ul><li>Internet network management framework </li></ul><ul><ul><li>MIB: management information base </li></ul></ul><ul><ul><li>SMI: data definition language </li></ul></ul><ul><ul><li>SNMP: protocol for network management </li></ul></ul><ul><ul><li>security and administration </li></ul></ul><ul><li>presentation services: ASN.1 </li></ul>
  3. 3. outline <ul><li>What is network management? </li></ul><ul><li>Internet-standard management framework </li></ul><ul><ul><li>Structure of Management Information: SMI </li></ul></ul><ul><ul><li>Management Information Base: MIB </li></ul></ul><ul><ul><li>SNMP Protocol Operations and Transport Mappings </li></ul></ul><ul><ul><li>Security and Administration </li></ul></ul>
  4. 4. What is network management? <ul><li>autonomous systems (aka “network”): 100s or 1000s of interacting hardware/software components </li></ul><ul><li>other complex systems requiring monitoring, control: </li></ul><ul><ul><li>jet airplane </li></ul></ul><ul><ul><li>nuclear power plant </li></ul></ul><ul><ul><li>others? </li></ul></ul>&quot; Network management includes the deployment, integration and coordination of the hardware, software, and human elements to monitor, test, poll, configure, analyze, evaluate, and control the network and element resources to meet the real-time, operational performance, and Quality of Service requirements at a reasonable cost.&quot;
  5. 5. Infrastructure for network management managed device managed device managed device managed device network management protocol definitions: managed devices contain managed objects whose data is gathered into a Management Information Base (MIB) managing entity agent data agent data agent data agent data managing entity data
  6. 6. Network Management standards <ul><li>OSI CMIP </li></ul><ul><li>Common Management Information Protocol </li></ul><ul><li>designed 1980’s: the unifying net management standard </li></ul><ul><li>too slowly standardized </li></ul><ul><li>SNMP: Simple Network Management Protocol </li></ul><ul><li>Internet roots (SGMP) </li></ul><ul><li>started simple </li></ul><ul><li>deployed, adopted rapidly </li></ul><ul><li>growth: size, complexity </li></ul><ul><li>currently: SNMP V3 </li></ul><ul><li>de facto network management standard </li></ul>
  7. 7. outline <ul><li>What is network management? </li></ul><ul><li>Internet-standard management framework </li></ul><ul><ul><li>Structure of Management Information: SMI </li></ul></ul><ul><ul><li>Management Information Base: MIB </li></ul></ul><ul><ul><li>SNMP Protocol Operations and Transport Mappings </li></ul></ul><ul><ul><li>Security and Administration </li></ul></ul><ul><li>ASN.1 </li></ul>
  8. 8. SNMP overview: 4 key parts <ul><li>Management information base (MIB): </li></ul><ul><ul><li>distributed information store of network management data </li></ul></ul><ul><li>Structure of Management Information (SMI): </li></ul><ul><ul><li>data definition language for MIB objects </li></ul></ul><ul><li>SNMP protocol </li></ul><ul><ul><li>convey manager<->managed object info, commands </li></ul></ul><ul><li>security, administration capabilities </li></ul><ul><ul><li>major addition in SNMPv3 </li></ul></ul>
  9. 9. SMI: data definition language <ul><li>Purpose: syntax, semantics of management data well-defined, unambiguous </li></ul><ul><li>base data types: </li></ul><ul><ul><li>straightforward, boring </li></ul></ul><ul><li>OBJECT-TYPE </li></ul><ul><ul><li>data type, status, semantics of managed object </li></ul></ul><ul><li>MODULE-IDENTITY </li></ul><ul><ul><li>groups related objects into MIB module </li></ul></ul>Basic Data Types INTEGER Integer32 Unsigned32 OCTET STRING OBJECT IDENTIFIED IPaddress Counter32 Counter64 Guage32 Time Ticks Opaque
  10. 10. SNMP MIB OBJECT TYPE: OBJECT TYPE: OBJECT TYPE: objects specified via SMI OBJECT-TYPE construct MIB module specified via SMI MODULE-IDENTITY (100 standardized MIBs, more vendor-specific) MODULE
  11. 11. SMI: Object, module examples <ul><li>OBJECT-TYPE: ipInDelivers </li></ul><ul><li>MODULE-IDENTITY: ipMIB </li></ul>ipInDelivers OBJECT TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION “ The total number of input datagrams successfully delivered to IP user- protocols (including ICMP)” ::= { ip 9} ipMIB MODULE-IDENTITY LAST-UPDATED “941101000Z” ORGANZATION “IETF SNPv2 Working Group” CONTACT-INFO “ Keith McCloghrie ……” DESCRIPTION “ The MIB module for managing IP and ICMP implementations, but excluding their management of IP routes.” REVISION “019331000Z” ……… ::= {mib-2 48}
  12. 12. MIB example: UDP module Object ID Name Type Comments UDPInDatagrams Counter32 total # datagrams delivered at this node UDPNoPorts Counter32 # underliverable datagrams no app at portl UDInErrors Counter32 # undeliverable datagrams all other reasons UDPOutDatagrams Counter32 # datagrams sent udpTable SEQUENCE one entry for each port in use by app, gives port # and IP address
  13. 13. SNMP Naming <ul><li>question: how to name every possible standard object (protocol, data, more..) in every possible network standard ?? </li></ul><ul><li>answer: ISO Object Identifier tree: </li></ul><ul><ul><li>hierarchical naming of all objects </li></ul></ul><ul><ul><li>each branchpoint has name, number </li></ul></ul> ISO ISO-ident. Org. US DoD Internet udpInDatagrams UDP MIB2 management
  14. 14. OSI Object Identifier Tree Check out
  15. 15. SNMP protocol <ul><li>Two ways to convey MIB info, commands: </li></ul>Managed device response Managed device trap msg request/response mode trap mode agent data managing entity agent data managing entity request
  16. 16. SNMP protocol: message types GetRequest GetNextRequest GetBulkRequest Mgr-to-agent: “get me data” (instance,next in list, block) Message type Function InformRequest Mgr-to-Mgr: here’s MIB value SetRequest Mgr-to-agent: set MIB value Response Agent-to-mgr: value, response to Request Trap Agent-to-mgr: inform manager of exceptional event
  17. 17. SNMP protocol: message formats
  18. 18. SNMP security and administration <ul><li>encryption: DES-encrypt SNMP message </li></ul><ul><li>authentication: compute, send MIC(m,k): compute hash (MIC) over message (m), secret shared key (k) </li></ul><ul><li>protection against playback: use nonce </li></ul><ul><li>view-based access control </li></ul><ul><ul><li>SNMP entity maintains database of access rights, policies for various users </li></ul></ul><ul><ul><li>database itself accessible as managed object! </li></ul></ul>
  19. 19. outline <ul><li>What is network management? </li></ul><ul><li>Internet-standard management framework </li></ul><ul><ul><li>Structure of Management Information: SMI </li></ul></ul><ul><ul><li>Management Information Base: MIB </li></ul></ul><ul><ul><li>SNMP Protocol Operations and Transport Mappings </li></ul></ul><ul><ul><li>Security and Administration </li></ul></ul><ul><li>The presentation problem: ASN.1 </li></ul>
  20. 20. The presentation problem <ul><li>Q: does perfect memory-to-memory copy solve “the communication problem”? </li></ul><ul><li>A: not always! </li></ul>problem: different data format, storage conventions struct { char code; int x; } test; test.x = 256; test.code=‘a’ test.code test.x test.code test.x host 1 format host 2 format a 00000001 00000011 a 00000011 00000001
  21. 21. A real-life presentation problem: aging 60’s hippie 2007 teenager grandma
  22. 22. Presentation problem: potential solutions <ul><li>1. Sender learns receiver’s format. Sender translates into receiver’s format. Sender sends. </li></ul><ul><ul><ul><ul><li>real-world analogy? </li></ul></ul></ul></ul><ul><ul><ul><ul><li>pros and cons ? </li></ul></ul></ul></ul><ul><li>2. Sender sends. Receiver learns sender’s format. Receiver translate into receiver-local format </li></ul><ul><ul><ul><ul><li>real-world-analogy </li></ul></ul></ul></ul><ul><ul><ul><ul><li>pros and cons? </li></ul></ul></ul></ul><ul><li>3. Sender translates host-independent format. Sends. Receiver translates to receiver-local format. </li></ul><ul><ul><ul><ul><li>real-world analogy? </li></ul></ul></ul></ul><ul><ul><ul><ul><li>pros and cons? </li></ul></ul></ul></ul>
  23. 23. Solving the presentation problem <ul><li>1. Translate local-host format to host-independent format </li></ul><ul><li>2. Transmit data in host-independent format </li></ul><ul><li>3. Translate host-independent format to remote-host format </li></ul>aging 60’s hippie 2007 teenager grandma
  24. 24. ASN.1: Abstract Syntax Notation 1 <ul><li>ISO standard X.680 </li></ul><ul><ul><li>used extensively in Internet </li></ul></ul><ul><li>defined data types , object constructors </li></ul><ul><ul><li>like SMI </li></ul></ul><ul><li>BER: Basic Encoding Rules </li></ul><ul><ul><li>specify how ASN.1-defined data objects to be transmitted </li></ul></ul><ul><ul><li>each transmitted object has Type, Length, Value (TLV) encoding </li></ul></ul>
  25. 25. TLV Encoding <ul><li>Idea: transmitted data is self-identifying </li></ul><ul><ul><li>T : data type, one of ASN.1-defined types </li></ul></ul><ul><ul><li>L : length of data in bytes </li></ul></ul><ul><ul><li>V : value of data, encoded according to ASN.1 standard </li></ul></ul>1 2 3 4 5 6 9 Boolean Integer Bitstring Octet string Null Object Identifier Real Tag Value Type
  26. 26. TLV encoding: example V alue, 5 octets (chars) L ength, 5 bytes T ype=4, octet string V alue, 259 L ength, 2 bytes T ype=2, integer
  27. 27. Network Management: summary <ul><li>network management </li></ul><ul><ul><li>extremely important: 80% of network “cost” </li></ul></ul><ul><ul><li>ASN.1 for data description </li></ul></ul><ul><ul><li>SNMP protocol as a tool for conveying information </li></ul></ul><ul><li>Network management: more art than science </li></ul><ul><ul><li>what to measure/monitor </li></ul></ul><ul><ul><li>how to respond to failures? </li></ul></ul><ul><ul><li>alarm correlation/filtering? </li></ul></ul>
  28. 28. <ul><li>Bandwidth, throughput, latency </li></ul><ul><li>Bandwidth utilization </li></ul><ul><ul><li>particularly important for ustomers </li></ul></ul><ul><ul><li>A common cause of performance problems </li></ul></ul><ul><li>Packets per second </li></ul><ul><li>Round Trip Time (RTT) </li></ul><ul><ul><li>It's a good measurement for long-term trend analysis </li></ul></ul><ul><li>Backbone packet loss </li></ul><ul><ul><li>Reach-ability -- Why is packet loss occurring? </li></ul></ul><ul><li>Circuit Performance -- How are our carriers doing? </li></ul>Performance: basic measurements
  29. 29. Measurement tools:BW and Throughput <ul><li>Bing : determines the real (raw, as opposed to available or average) throughput on a link by measuring ICMP echo requests roundtrip times for different packet sizes for each end of the link. </li></ul><ul><li>bprobe/cprobe : estimates the maximum possible bandwidth along a given path. cprobe estimates the current congestion along a path. Currently these tools rely on two features of the IRIX operating system for SGI hardware. </li></ul><ul><li>Netperf : Netperf is a benchmark that can be used to measure the performance of many different types of networking. It provides tests for both unidirecitonal throughput, and end-to-end latency. </li></ul><ul><li>nettimer : nettimer is useful for measuring end-to-end network performance. </li></ul><ul><li>ttcp and nttcp : classic throughput benchmark or load generator. </li></ul>
  30. 30. Measurement Tools: Forward path probes <ul><li>ping </li></ul><ul><li>Pingplotter : visual version of ping </li></ul><ul><li>Traceroute : Directs a packet to each router along a path without actually knowing the path, by setting the IP TTL field from 1 to n until the ultimate destination is reached. Upon receiving a packet with an expired (0) TTL, the hop generates an ICMP Time Exceeded response back to the source, thus identifying the hop and its round trip delay. Each UDP packet is sent to a probably-unused port, so when the destination receives the packet it responds with ICMP Port Unreachable. </li></ul><ul><li>Xtraceroute : Graphical traceroute. </li></ul>traceroute: Univ. of Arizona to Tennessee Tech
  31. 31. Measurement tools: Link utilization <ul><li>IPTraf : IPTraf is a console-based network statistics utility for Linux. It gathers a variety of figures such as TCP connection packet and byte counts, interface statistics and activity indicators, TCP/UDP traffic breakdowns, and LAN station packet and byte counts. </li></ul><ul><li>Iperf : Iperf is a tool to measure maximum TCP bandwidth, allowing the tuning of various parameters and UDP characteristics. Iperf reports bandwidth, delay jitter, datagram loss. </li></ul><ul><li>Tcpdump : Stable, mature, canonical portable packet collector. </li></ul>
  32. 32. One-way Availability/Latency Tests <ul><li>Echoping : Echoping is a utility for measuring TCP/UDP latency by sending to an arbitrary (default 'echo') port. It includes support for testing HTTP query latency. </li></ul><ul><li>Fping : A ping variant suitable for use in scripts. fping will issue ICMP echo requests to a list of hosts in round-robin fashion. fping output is meant to be parsed by scripts. </li></ul><ul><li>Gnuplotping : Pings multiple hosts in parallel, with graphical display (gnuplot) of delay distribution. </li></ul><ul><li>Imeter : Imeter is a series of scripts that supports collection, analysis, and web-displayed graphs of long-term ping data. </li></ul>
  33. 33. References: <ul><li>NLANR: http:// /NPMT/ </li></ul><ul><li>A Compendium of Network Performance Measurement Resources by Kai Chen </li></ul><ul><li>Internet Protocol Performance Metrics </li></ul><ul><li>Introduction to Network Performance Measurement by Daniel McRobb </li></ul><ul><li>Network Performance Measurement and Analysis -- Part 1: A Server-Based Measurement Infrastructure by Y. Thomas Hou, Yingfei Dong, Zhi-Li Zhang </li></ul><ul><li>NIMI - A System for Flexible Network Performance Measurement by A.Adams and M.Mathis </li></ul>